An image typically has many properties—including for example, hue, tint, shade, tone, brightness, lightness, chroma, contrast, and so on. For example, hue defines color in terms of, for example, red, green or magenta. Hue also defines mixtures of two pure colors like red-yellow (e.g., orange), yellow-green, or the like. A tint is a mixing result of an original color to white. If an image has been tinted, it implies that white has been added to the original color. A shade is a mixing result of an original color to black. If an image has been shaded, it implies that black has been added to the original color. A tone implies a result of mixing a pure color with any neutral/grayscale color, including the two extremes white and black. Brightness is an attribute of human perception, which is mainly influenced by a color's lightness. For one color of specific hue, the perception of brightness is also more intense if saturation is increased. A higher level of saturation makes a color look brighter. Lightness defines a range from dark (0%) to fully illuminated (100%). Any original hue has an average lightness level of 50%. A chromatic signal is a component of color perception that is not achromatic, i.e. any deviation from neutral-color perception (dark, grayscale, etc.). A chromatic intensity or chromaticity is an intensity of the chromatic signal contributing to color perception. Chroma is a component of a color model. For example, there is a blue-yellow and a red-green chroma component. The contrast of an image can be defined as a difference between a darkest area and a brightest area of various objects, or as a difference between a darkest area and a brightest area of different regions within a common view of the image. Increasing contrast of the image increases the difference between dark and bright areas of the image, while decreasing contrast of the image decreases the difference between dark and bright areas of the image. It is desirable, for aesthetic, visual, or other reasons, to easily modify or adjust a property (e.g., the contrast) of an image.